The targetted collision energy of 14 TeV for the LHC is most appropriate to investigate physics around the electroweak scale about 246 GeV and somewhat above. For the up to now by the LHC probed energy of 8 TeV and considering the analysis of the data done so fare, the standard model seems to work rather well at these scales so it seems natural to parameterize the observations by the standard model until new physics shows up.
String theory however is first of all a quantum gravity theory and large observable effects of it would most naturally appear at the quantum gravity scale which is much higher (about the Planck scale of about $10^{19}$ GeV) than the by the LHC directly reachable energy scale.
Nevertheless, it could well be that string theory and other higher energy BSM physics has low energy effects that can in principle be seen at the LHC. High energy phenomenology is the part of particle physics which tries to predict such effects. For example string phenomenology is a growing industry and this paper gives a somewhat broader overview about potentially observable low energy phenomenological effects of Planck scale physics.
Technically speaking the standard model is a good effective theory to describe physics around the electroweak scale, and it is expected to be linked by renormalization to a more general theory (for example string theory) needed to describe physics at the Planck scale. Any unified theory that is any good has to be able in principle to reproduce the standard model as an effective theory.
To come to the point, since the GUT or quantum gravity scale (where the strength of gravity is expected to become comparable to the other three forces) are widely separated from the energy scale probed by the LHC up to now are widely separated and no strong hints of new physics has turned up so far, I agree with Matt Strassler that it is better to focus on standard model physics in texts about CERN and the LHC in texts targetted at an audience of non experts. But this does not mean that doing BSM physics and looking for hints of it is not important and as Urs Schreiber nicely explains, String theory is even useful for doing standard model calculations that would not have been possible without these insights. And as Lubos says in a comment (if I understand him right), as string theory in principle contains the standard model as an effective theory at the electrowea scale, trying to apply pure string theory calculations to the observations at the LHC is just a more complicated reparameterization.